The overall aim of this proposal is to study the biochemical mechanisms involved in the induction of bladder cancer in experimental animals. Primary emphasis will be given to study of the mechanism of action of the carcinogens butyl (4-hydroxybutyl) nitrosamine and butyl- (4-carboxypropyl) nitrosamine and their metabolites in the induction of bladder cancer in the rat. These compounds will also be tested for carcinogenicity in the rabbit.